1. Field of the Invention
The present invention relates to magnetic gauging systems and more specifically to an apparatus for gauging the thickness of coatings on metal products.
The present invention is applicable for gauging the thickness of nickel coatings on a ferromagnetic or nonmagnetic base, as well as for gauging the thickness of nonmagnetic coatings on a ferromagnetic base.
2. Description of the Prior Art
Known in the present state of the art is an apparatus for gauging the thickness of coatings on metal products, based on gauging the force of attraction of a permanent magnet to the product being gauged (cf. U.S. Pat. No. 3,716,779, Cl. 601 B). Said apparatus comprises a casing which accommodates a wheel system; a spring actuator linked to one of the members of said wheel system to impart rotation thereto; two levers, independently balanced in a static state, the first of which carries a gauging permanent magnet adapted to interact, by virtue of its field, with the ferromagnetic coating of a product or with a base thereof in case of a nonmagnetic coating, while the second lever is adapted to interact with the first balanced lever in cases where the pulling force of the latter lever is not high enough for the gauging permanent magnet to break away from the product being gauged; two coiled springs, the first of which is connected, through one of its ends, with the first balanced lever and through its other end with one of the shafts of the wheel system, whereas the second coiled spring with one of its ends is connected with the second balanced lever and through the other end thereof, with the casing in such a manner as to adjust the tension of the spring; a magnetic element attached to the casing so as to attract the product being gauged; a reset lever to return the first balanced lever into the initial position, said lever being locked-in with the central pivot shaft of the wheel system, said shaft carrying the winding knob and a pointer to indicate the gauged thickness on the circular scale rigidly fixed in position on the casing.
When winding up the apparatus by rotating the winding knob on the central shaft of the wheel system, the end of the gauging permanent magnet goes beyond the bearing plane of the apparatus casing, whereupon the wheel system is locked.
Upon putting the gauge onto the product to be gauged the end of the gauging permanent magnet gets flush with the bearing surface of the casing, the wheel system starts rotating under the action of the spring actuator, with the result that the former coiled spring is twisted until the gauging permanent magnet is broken away from the product being gauged. At the instance of break away of the gauging permanent magnet the first balanced lever rotates round its axis, and the brake spring fixed thereon stops rotation of the brake wheel incorporated into the wheel system of the apparatus, and thus stops the entire wheel system.
Once having been broken away from the product being gauged, the gauging permanent magnet is attracted by the magnetic element, thereby affording more reliable braking.
The afore-described known apparatus is capable of gauging a broad range of coating thicknesses due to the provision of a second balanced lever with an adjustable spring tension.
However, said apparatus offers some difficulties when winding up by rotating the winding knob whose torque is not adjustable.
It is therefore a primary object of the present invention to provide an apparatus for gauging the thickness of coatings on metal products having such a constructional arrangement of the winding up means thereof that would provide rapid and convenient winding up of the apparatus and would increase its efficiency.